FIXED! Solution is unknown, the problem just sort of resolved itself I guess. After going through about 15 fresh installs, I guess it finally fixed itself.
After some more playing around, it seems to be whenever something changes. I don't know if it is a lag problem, but it has never had this problem before.
What I mean by changes;
Selection changes. Like when I am in Clothes menu, I have to hold down the right arrow to change Upper, or Hats, or something like that.
http://gyazo.com/ee53c6bd47be51000de2a4dd9ae8e401
Also, everything worked about 3 days ago. I installed a new pack, and then everything started glitching. I then uninstalled and reinstalled the game, and it didn't fix.
I am having problems with SNT. Lately, I have needed to spam my selection key hard, for about 2 minutes for it to finally load. All other stuff (Up and down, left and right) work fine.
Stuff I have tried;
New keyboard
Fresh trainer
Fresh game
Re-install
Change Selection key